/**
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements. See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership. The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.rdf.simple;
  
  import java.util.IllformedLocaleException;
  import java.util.Locale;
  import java.util.Objects;
  import java.util.Optional;
  
  import org.apache.commons.rdf.api.IRI;
  import org.apache.commons.rdf.api.Literal;
  
  /**
   * A simple implementation of Literal.
   */
  final class LiteralImpl implements Literal, SimpleRDF.SimpleRDFTerm {
  
      private static final String QUOTE = "\"";
  
      private final IRI dataType;
      private final String languageTag;
      private final String lexicalForm;
  
      public LiteralImpl(final String literal) {
          this(literal, Types.XSD_STRING);
      }
  
      public LiteralImpl(final String lexicalForm, final IRI dataType) {
          this.lexicalForm = Objects.requireNonNull(lexicalForm);
          this.dataType = Types.get(Objects.requireNonNull(dataType)).orElse(dataType);
          if (Types.RDF_LANGSTRING.equals(this.dataType)) {
              throw new IllegalArgumentException(
                      "Cannot create a non-language literal with type " + Types.RDF_LANGSTRING);
          }
          this.languageTag = null;
      }
  
      public LiteralImpl(final String literal, final String languageTag) {
          this.lexicalForm = Objects.requireNonNull(literal);
          this.languageTag = Objects.requireNonNull(languageTag).toLowerCase(Locale.ENGLISH);
          if (languageTag.isEmpty()) {
              // TODO: Check against
              // http://www.w3.org/TR/n-triples/#n-triples-grammar
              throw new IllegalArgumentException("Language tag can't be null");
          }
          try {
              new Locale.Builder().setLanguageTag(languageTag);
          } catch (final IllformedLocaleException ex) {
              throw new IllegalArgumentException("Invalid languageTag: " + languageTag, ex);
          }
  
          // System.out.println(aLocale);
          this.dataType = Types.RDF_LANGSTRING;
      }
  
      @Override
      public IRI getDatatype() {
          return dataType;
      }
  
      @Override
      public Optional<String> getLanguageTag() {
          return Optional.ofNullable(languageTag);
      }
  
      @Override
      public String getLexicalForm() {
          return lexicalForm;
      }
  
      @Override
      public String ntriplesString() {
          final StringBuilder sb = new StringBuilder();
          sb.append(QUOTE);
          // Escape special characters
          sb.append(getLexicalForm().replace("\\", "\\\\"). // escaped to \\
                  replace("\"", "\\\""). // escaped to \"
                  replace("\r", "\\r"). // escaped to \r
                  replace("\n", "\\n")); // escaped to \n
          sb.append(QUOTE);
  
          // getLanguageTag().ifPresent(s -> sb.append("@" + s));
          if (getLanguageTag().isPresent()) {
              sb.append("@");
             sb.append(getLanguageTag().get());
 
         } else if (!getDatatype().equals(Types.XSD_STRING)) {
             sb.append("^^");
             sb.append(getDatatype().ntriplesString());
         }
         return sb.toString();
     }
 
     @Override
     public String toString() {
         return ntriplesString();
     }
 
     @Override
     public int hashCode() {
         return Objects.hash(lexicalForm, dataType, languageTag);
     }
 
     @Override
     public boolean equals(final Object obj) {
         if (this == obj) {
             return true;
         }
         if (obj == null || !(obj instanceof Literal)) {
             return false;
         }
         final Literal literal = (Literal) obj;
         return getDatatype().equals(literal.getDatatype()) && getLexicalForm().equals(literal.getLexicalForm())
                 && getLanguageTag().equals(literal.getLanguageTag());
     }
 
 }